Among people in Boravia who had a car accident while driving, 4 percen

Among people in Boravia who had a car accident while driving, 4 percent of those under 50 years old were found to have prosinopsis, a currently untreatable eye disease that causes a gradual deterioration In peripheral vision. Yet the proportion of drivers under 50 who have been diagnosed with prosinopsis is only 2 percent in Boravia. Clearly, therefore, having the disease makes Boravian drivers under 50 significantly more likely to have a car accident.

Which of the following is an assumption on which the argument depends?

A. Among Boravians under 50 who had a car accident while driving, most of those who had prosinopsis had the disease in its late stages.
B. Prosinopsis is not more difficult to diagnose in a person under 50 than in someone older.
C. There is no way of correcting for deterioration in peripheral vision brought about by prosinopsis.
D. Boravian drivers under 50 who have prosinopsis have generally been diagnosed as having it.
E. Prosinopsis has no symptoms other than the deterioration of peripheral vision.

Source: topgmat